In large reactors such as those used in heavy oil desulfurization, the reaction products such as coke and catalyst are often consolidated (i.e., form a coagulated mass) because of thermal or chemical effects that occur during the reaction, and such consolidated catalysts cannot be simply discharged from the bottom of the reactor. Conventionally, operators have to enter the reactor and crush the consolidated waste catalyst with a suitable machine to reduce the catalyst to sufficiently small pieces to enable them to be discharged from the reactor. It has been described that the waste catalyst can be crushed with an explosive, gunpowder, or an inflammable gas and air mixture that is charged into a hollow pipe and ignited to cause an explosion which will fracture the catalyst into sufficiently small pieces to enable them to be easily discharged from the reactor. See Japanese Patent Application (OPI) Nos. 27776/1975 and 69652/1975 and Japanese Patent Publication No. 47747/1977 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application").
The use of a crushing machine involves considerable time in crushing the waste catalyst into small pieces and discharging them from the reactor. Furthermore, in order to avoid combustion and other chemical changes that would occur in the waste catalyst as a result of contact with air, the reactor must be sealed with an inert gas, which necessitates taking precautions to ensure safety and involves an inefficient operation.
On the other hand, the use of explosives, gunpowder, or a mixture of inflammable gas and air is a very effective method. However, great skill is required in determining the proper amount of explosive, etc., to be primed, and this method is not applicable to the waste catalyst around inner walls or accessories such as pipes and trays of the reactors which might be damaged by explosion. In addition, the fracturing operation cannot be started until the catalyst is completely cooled after the lapse of an extended period of time.